Drivers and impacts of the seasonal weather in the UK

March 2014 - The UK has seen a run of seasonal weather over recent years that has had impacts and led to disruption across the country. The question for climate science is whether this seasonal weather is only part of the natural variability we expect, or if there is any connection to our changing climate. This synthesis paper investigates the role of natural variability and climate change in shaping these seasons.

The UK has just experienced an exceptionally wet winter. Overall England and Wales have experienced their wettest January and winter season (December to February) since records began in 1766. The winter of 2013/14 is the latest in a run of seasonal weather that has had large impacts on the UK and across Europe over recent years, for example the cold winter of 2010/11, the wet summer of 2012 and the cold spring of 2013. This paper looks at recent examples in the context of seasons that are too hot, too cold, too wet or too dry.

In September 2013 Working Group I (WGI) of the Intergovernmental Panel on Climate Change published its 5th Assessment Report (AR5). It concluded that warming of the climate system is unequivocal, and it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. This paper focuses on what this means for the UK and addresses the question of what the role of climate change and natural variability is in extreme seasons.

Research shows that when viewed over long-term averages, the UK is expected to see more frequent milder, wetter winters and more frequent hotter, drier summers in the future. The role of human influence on our climate is already detectable on summertime heat waves. But the UK has seasonal weather that also varies hugely from year to year due to natural processes.

Further research is urgently needed to deliver robust detection of changes in storminess and daily/hourly rain rates. The topics considered here represent substantial scientific challenges but new observing systems and higher resolution computational models of the climate system coming online now are providing new insights that promise progress and the continuing improvement of UK adaptation advice.